Size control of self-assembled nanoparticles by an emulsion/solvent evaporation method

Minsu Lee, Yong Woo Cho, Jae Hyung Park, Hesson Chung, Seo Young Jeong, Kuiwon Choi, Dae Hyuk Moon, Sang Yoon Kim, In San Kim, Ick Chan Kwon

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55 Citations (Scopus)


A novel and simple method for size control of self-assembled nanoparticles is suggested in this paper. Polymeric nanoparticles were prepared from amphiphilic chitosan derivatives fluorescein isothiocyanate (FITC)-conjugated glycol chitosans (FGCs). The attachment of hydrophobic FITC onto hydrophilic glycol chitosan induced the amphiphilic conjugate to form self-assembled nanoparticles in aqueous media, depending on degree of substitution. The size of self-assembled nanoparticles was controlled by a novel emulsion/solvent evaporation method. Adding a small amount of an immiscible solvent with water (chloroform) to FGC nanoparticle suspensions in aqueous media followed by ultrasonification and solvent evaporation led to partial dissociation and subsequent reformation of nanoparticles. The evaporation of chloroform facilitated the hydrophobic association, which resulted in more dense and hardened hydrophobic cores. The size of nanoparticles was closely related with the FGC concentration in the emulsion. The mean diameters of self-assembled nanoparticles were 150-500 nm at the FGC concentrations of 0.3-2.5 mg/ml. Higher FGC concentration resulted in larger particles. The polydispersity factors (μ22) of the reformed nanoparticles were fairly low (0.001-0.094), indicating narrow size distribution. The FGC nanoparticles were stable in phosphate-buffered saline at 37°C up to 20 days. Lactose was a good excipient for maintaining the structural integrity of nanoparticles during freeze-drying. Without lactose, the freeze-dried nanoparticles were not homogeneously redispersed in aqueous media. However, the freeze-dried nanoparticles with lactose were spontaneously redispersed in aqueous milieu with their own sizes.

Original languageEnglish
Pages (from-to)506-512
Number of pages7
JournalColloid and Polymer Science
Issue number5
Publication statusPublished - 2006 Feb


  • Colloidal stability
  • Fluorescein isothiocyanate
  • Glycol chitosan
  • Lactose
  • Nanoparicles
  • Size control

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry


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